I came across an interesting article No, One Quake Did Not Lead to Another, in New York Times Online. The article pointed out that following Hawaii’s 6.7 quake on October 15, two other big quakes occurred, a 6.8 near Papua New Guinea, and a 6.4 off the coast of Peru. People wondered, Are these quakes related? A seismologist at the University of Hawaii indicated that generally they are not related.

I remember the first earthquake that I “felt” was one afternoon on the campus of Ohio State University in late sixties. Columbus, Ohio is located in the middle of the continent, and far from the edges of any of the Earth’s tectonic plates. What caused this quake? Surely not the movement of the Earth’s plates.

This quake occurred on November 9, 1968. The epicenter of the quake was in South-Central Illinois, hundreds of miles from Columbus. The quake was felt hundreds of miles from the epicenter in Illinois, was part of the New Madrid Fault Zone. The 1968 quake was 5.5 in the Richter Scale. The map below shows the distribution and intensity of earthquakes in the New Madrid Fault Zone from 1975 – 1995.

So here in the middle of the continental US is an active earthquake zone unrelated to the earthquakes that occur along the edges of plates, such as along the San Andreas Fault.

The Hawaii quakes are in the middle of the Pacific Plate, far from the edges. The quakes that occured in Papua New Ginea and off the coast of Peru are along the rim of the Pacific Plate, and are related to the movements that occurr along the edges of plates. Where do you live? Has an earthquake recently occurred where you live? Go to this site, or look at the map below to find out.

Map: Earthquakes, October 15 – 22, 2006